Usually, in a wireless communication system that includes a mobile station and a base station, at the time of initial access, reconnection, or handover, a mobile station carries out a negotiation operation by transmitting a connection setup request signal for a connection setup request to a base station. In addition, in recent years, the standardization of Long Term Evolution (LTE) that is one of the specifications relating to data communication in a wireless communication system has been promoted in the 3rd Generation Partnership Project (3GPP).
The initial access being taken as an example of the negotiation, the mobile station arbitrarily selects the sequence number of a connection setup request signal, and transmits the connection setup request signal to the base station. In this regard, however, when the mobile station makes a connection setup request, resources that use a connection setup request signal are not divided depending on whether a call is an emergency call or a nonemergency normal call. Therefore, in a case in which the connection setup request is made, when a congestion state occurs owing to heavy traffic on the lines, the connection setup request is likely to be made using a signal sequence that corresponds to the same sequence number, and hence the competition between connection setup requests occurs. Therefore, emergency calls that are expected to be preferentially connected may also be congested.
Accordingly, in recent years, there has been proposed a technique in which resources for connection setup request signals are grouped for individual objects of connection setup requests. Here, a processing flow of the related art in which resources are grouped for individual objects of connection setup requests will be described with reference to FIG. 30. FIG. 30 is a flowchart of a processing operation of the related art in which resources are grouped for individual objects of connection setup requests. In addition, in FIG. 30, a mobile station is indicated as user equipment (UE), and a base station is indicated as an evolutional Node B (eNB).
For example, the eNB performs the grouping of random access channel (RACH) resources, and transmits the grouping result as system information or a paging message to the UE. For example, the RACH resources means resources, which are common channels that a plurality of UEs may use, for individual objects such as initial access, handover, synchronization retention, access termination, a wireless resource request, and the like. In other words, for example, the grouping of the RACH resources means that resources for the individual objects are divided among connection setup request signals that are used for normal calls or emergency calls.
On the other hand, for example, the UE selects a signature and a RACH event, and makes a connection setup request to the eNB. In addition, for example, when the eNB receives the connection setup request from the UE, the eNB transmits to the UE a connection setup request response that is a response for the connection setup request. After that, for example, when the UE receives the connection setup request response from the eNB, the UE transmits uplink data to the eNB.